A concept for the generalization of the standard electrokinetic model

Based on recent progress in the measurement and interpretation of ion accumulation and motion in the stagnant part of the electrical double layer (DL), a generalized standard electrokinetic model (GSEM) is proposed. The suggested model reflects a new standard for the modeling of electrokinetic transport. In distinction to earlier models, the occurrence of conductivity in the stagnant layer is assumed. In consequence, the GSEM is distinguished by the fact that there is no demand with respect to smoothness of the solid surface on the molecular level. Within the framework of the GSEM, the electrical DL is described by at least two parameters: zeta and K-sigma. The combined experimental determination of the two parameters, comprising two electrosurface phenomena, is discussed as a means to determine the distribution of adsorbed ions between the diffuse layer and the Stem layer. Integrated electrosurface investigations in a broad vicinity of the isoelectric point are proposed for the discrimination between two different mechanisms of ionic conductivity in the stagnant layer. (C) 2001 Elsevier Science B.V. All rights reserved.